PROJECT SUMMARY The development of a vaccine capable of providing protective and long-lasting immunity against HIV-1 will most likely rely on the effective priming of HIV-1 specific T cell responses by dendritic cells (DC). However, previous attempts to develop a DC-based HIV vaccine used Monocyte-Derived-DCs (MMDCs) instead of primary cells, with very limited success sustaining long lived memory HIV-1-specific T cell responses overtime. In addition, less studies evaluated the potential of manipulating DC to direct efficient priming of cellular vs humoral adaptive immune responses against HIV-1, specially in accessible in vivo models relevant for human DC and HIV-1 vaccine research. We previously showed that cDC from different subgroups of HIV-1 controllers are specialized to prime distinct types of HIV-1 specific adaptive immune responses. In one hand, cDCs from HIV-1 elite controllers (EC) have enhanced abilities to sense HIV-1 trough the cGAS/STING/TBK1 pathway and efficiently activate polyfunctional HIV-1 specific CD8+ T cells. In the other hand, cDCs from neutralizer controllers (NC) who develop HIV-1 specific antibodies with broader neutralizing activity, are more efficient priming nave CD4+ T cells into T follicular helper cells (Tfh) due to activation of specific cytokine receptors. In the proposed project, we hypothesize that priming of effective HIV-1 specific cellular vs humoral adaptive immune responses in vivo will require distinct adjuvant strategies to tailor cDC function. To address this question, we propose to test two novel DC-based vaccine strategies based on the use of adjuvants designed to selectively activate different innate activation pathways in primary cDCs to induce EC or NC-like functional phenotypes and therefore, enhance the priming of either HIV-1 specific cytotoxic CD8+ T cell or CD4+ T follicular helper cell responses separately in vivo. To this end, we will use humanized bone marrow, liver and thymus (BLT) mice as our in vivo system, where HIV-1 specific adaptive immune responses can be induced. Using this strategy, we will determine the ability of adjuvant treated EC-like cDCs to induce HIV-1-specific CD8+ T cells able to control HIV-1 replication in vivo. In the other hand, we will evaluate if enhanced priming of CD4+ Tfh by NC-like cDCs contributes to improving HIV-1 humoral responses in the BLT mouse, which are limited in this model. Together, this study will provide critical information about the molecular ingredients required to boost the priming of adaptive immunity against HIV-1 in vivo. Thus, this newly acquired knowledge will lead the way for future designs of an effective HIV-1 vaccine.